Mikrotik not allowing me to use a new internet connection

RouterOS General
1

Hi, we have a Mikrotik 750G,
ether1: new fibre connection
ether2: adsl connection
ether3: 4g connection
ether4: 4g connection
ether5: LAN connection

Ether 1/2/3/4 have Master Port set to none

My new fibre connection:
IP Address: 203.153.240.26
Subnet Mask: 255.255.255.252
Default Gateway: 203.153.240.25 (actual fibre box)

In my address list I have added a new address:
address: 203.153.240.26/24
Network: 203.153.240.0
Interface: ether1

Route List:
Dst. Address: 0.0.0.0/0
Gateway: 203.153.240.25 (reachable)
Type: unicast
Distance: 1
Scope: 30
Target Scope: 10
Routing Mark: (ether1)

I have set my pc’s ip address in Firewall/Address Lists to use the (ether1) connection, but my internet does not work.
I have connected directly to the fibre to check the internet connection and it works fine.

Any ideas, anyone?
mikrotik.docx (193 KB)

2

Shouldn’t this be

address: 203.153.240.26/30

Also, are you NATting (src-nat) traffic egressing on ether1?

3

Hi, when I changed the address to 203.153.240.26/30, the network below changes to 203.153.240.24, this IP does not exist, but in the route list it shows up as reachable.
Yes I am NATting (src-nat) traffic egressing on ether1.

NAT Rule
Chain: srcnat
Dst. Address: 203.153.240.26
Out. Interface: ether1
Action: src-nat
To Address: 203.153.240.25 (.25 is the address of the fibre box)

Still no internet!

4

I spoke to a mate back in South Africa and he asked to to add
CHAIN (srcnat) SRC. ADDRESS (192.168.10.0/24) OUT INTERFACE (your 4g conn) ………. ACTION TAB > MASQUERADE

This works like a charm!

5

You said that the subnetmask was 255.255.255.252. This equates to 30 bits. This means that your network address is 203.153.240.24, usable addresses are 203.153.240.25 and 203.153.240.26 and your broadcast address is 203.153.240.27.

Yes I am NATting (src-nat) traffic egressing on ether1.

The next suggestion would have been to have checked the NAT rule. Seems you’ve done that and it now works!

6

The to-address should be your router address!